Of ongoing interest is the evaluation of the oxygen permeability of newly available contact lenses for correlation with corneal oxygen needs under various conditions of lens wear. Of particular importance is the evaluation of therapeutic contact lenses at typical thicknesses and comparison of their oxygen permeability as found in the laboratory to their clinical performance. Hydrophilic polymer derived from methacrylic acid and copolymers therefrom have been widely researched in recent years. As biomaterials for intraocular implants, these hydrogels have suffered due to their relatively low strength. We are currently investigating hydrophilic polymers derived from acrylic acid and copolymers therefrom. These materials have been effectively applied as episcleral implants in retinal detachment surgery, among other applications where a high strength implant material is desired. We will also test sustained delivery of nitrosourea derivatives released from episcleral silicone rubber implants to experimental melanomas transplanted into the anterior chamber of rabbit eyes. In vitro tests have demonstrated constant rates of release of the nitrosoureas from silicone implants. However, the instability of these drugs limits the amount that can be released from a single implanted capsule. Thus, refillable implants provide prolonged, constant release of these anticancer agents. Sustained release at the malignancy site is expected to decrease the systemic toxicity that takes place when these drugs are administered systemically.